1. Field of the Invention
This invention relates a formation method and formation device for forming 2-dimensional code using laser marking, and more particularly to a formation method and formation device for forming 2-dimensional code that is suitable for managing traceability of single products, or electronic or electrical equipment, machinery, automobiles, housing materials and the like that are made by assembling a plurality of parts, or all kinds of products that include these kinds of parts.
2. Description of the Related Art
When performing product quality control, manufacturing-history information, such as product-quality data for parts or raw materials that are used in manufacturing, adjustment data, which is used when adjusting manufacturing conditions such as temperature, time, dimension and the like, or when making product adjustments, or inspection data, which is obtained when inspecting products, is managed in a database of the product manufacturer.
In order to access the manufacturing histories for individual products that are recorded in this database, a product number is assigned to the product. For example, a nameplate may be attached to products such as electrical equipment, and the name of the manufacturer, product name and number (serial number), and the like are printed on that nameplate.
Also, in a case such as when there is an inquiry regarding product quality from a user who purchased a delivered product, by searching the database based on the serial number or the like, it is possible to access the manufacturing history of that product, and to provide that information.
Moreover, by accumulating defect information, claims or the like, and sending this information to the development and manufacturing departments as feedback, it is possible to reflect that information in the manufacturing process and prevent the manufacture of defective products.
Furthermore, there is known technology in which instead of accessing a database, the manufacturing-history information is converted to 2-dimensional code, and a printed label or the like on which this converted 2-dimensional code is printed is attached or applied to the product, and the product manufacturing-history information is obtained directly from that 2-dimensional code (refer to Japanese published patent application No. 2003-140726).
However, in the methods described above of storing manufacturing-history information in a database or 2-dimensional code, even though it was possible to obtain history information for a product, it was not possible to obtain history information for each individual part of the product.
Also, even though it may have been possible to identify a defective part from information such as defect information, claims or the like, it was not possible to obtain the manufacturing-history information for that defective part, or it took a long time to access the manufacturing-history information for a defective part, so there were problems in that it was not possible to effectively avoid manufacturing defective parts, or it took a long time until it was possible to avoid manufacturing defective parts. Also, it required much time to respond to inquiries or claims from a consumer regarding product quality.
In the case of 2-dimensional code, the code size is changed according to the amount of information. For example, in the case where the cell size is 1 mm and the data to be coded is ‘01234’, the 2-dimensional code that is generated is as shown in FIG. 28A. The 2-dimensional code that is shown in FIG. 28A is 10 cells (vertical)×10 cells (horizontal), and the overall size is 10 mm×10 mm. On the other hand, in the case where the data to be coded is ‘0123456789’, the 2-dimensional code that is generated is as shown in FIG. 28B. The 2-dimensional code shown in FIG. 28B is 12 cells (vertical)×12 cells (horizontal), and the overall size is 12 mm×12 mm. The size of the 2-dimensional code differed in this way according to the amount of stored information.
In order to mark different data using the same size, technology has been proposed in which first, the code size is specified, and then it is possible to form 2-dimensional code having a desired size (see Japanese published patent application No. H11-167602).
However, in the prior art disclosed in the aforementioned patent document 1, laser marking is performed for cells that will be black cells using a spiral-shaped plotted pattern, so there is a problem in that controlling the operation of the laser device becomes difficult. Also, by specifying the code size, it is possible for 2-dimensional code to have a desired size, however, since spiral-shaped laser printing is performed, in order to print the specified size, it is necessary to control the operation of the laser with high precision. Furthermore, since laser marking is performed using a spiral-shaped plotted pattern, there is a problem in that forming an extremely minute 2-dimensional code becomes difficult.